1. Field of the Invention
The present invention relates to a semiconductor device and a method of manufacturing thereof, and particularly to a semiconductor device having a semiconductor element and a resistor and to a method of manufacture thereof.
2. Description of the Related Art
Recently, the miniaturization and integration of the semiconductor device is progressing, and various attempts are made to form many semiconductor elements on a small surface of a semiconductor chip. Further, the semiconductor device formed with the semiconductor elements may be provided with a ladder circuit which splits a voltage.
Further, forming the ladder circuit on a small surface is a very important aspect in miniaturizing and integrating the semiconductor chip.
Conventionally, in order to miniaturize the ladder circuit, for example, as stated in Japanese Patent Application Laid-open No. Hei 9-51072, miniaturization and integration of the ladder circuit is attempted by forming an insulating film on a first resistor formed in a field region, and forming a second resistor on the insulating film to form a resistor with a two layer structure. Shown in FIG. 16 is a two layer structure where a first layer resist 77 and a second layer resist 66 are formed in a field region of a semiconductor substrate 75 in the thickness direction of the semiconductor substrate 75 through an interlayer insulating film 78.
However, when the two layer structure resistor is used, there is a problem in that the manufacturing steps are complicated and the manufacturing cost increases, and also it becomes difficult to have a specific accuracy equal to or more than that of the ladder circuit formed with the resistor which is formed above the conventional field region.
Further, conventionally the resistor was formed on only the field region, and the top of the active region was not used at all for miniaturization and integration of the semiconductor device regarding the arrangement of the resistor. Therefore, when forming the resistor on the semiconductor device, an area added with an area formed with a semiconductor element and an area formed with a resistor is necessary on the semiconductor substrate. Accordingly, if a resistor is formed on also the active region, the area of the whole semiconductor device may be made smaller. Thus, miniaturization and integration of the semiconductor chip may be further progressed. Further, since the area of the region where the resistor may be formed becomes larger, it becomes possible to use a substance with relatively small resistance and also to avoid a two layer structure of a resistor. Further, by leveling the insulating film below the resistor by CMP or the like, the conventional specific accuracy may be easily obtained. Note that, an active region refers to a region on the semiconductor substrate where a transistor and the like are formed.
Incidentally, when a resistor is formed on the active region, a special device is necessary in order to contact the resistor appropriately.
A first object of the present invention is to provide a semiconductor device, for example, a bleeder circuit, which is miniaturized and integrated. Further, the object is to provide a semiconductor device which uses such a bleeder resistance circuit with high accuracy, low cost and a small temperature coefficient, for example, a semiconductor device such as a voltage detector or a voltage regulator, with a small area.
Further, a second object of the present invention is to provide method of manufacturing a semiconductor device that is miniaturized and integrated, including a method of forming a contact to a resistor formed on the semiconductor device.
According to the present invention, there is provided a semiconductor device formed with a resistor on, for example, an active region formed with a semiconductor element such as a field effect transistor, of a semiconductor substrate through, for example, an insulating film leveled by CMP or the like. Thus, the first object is achieved.
Further, according to the present invention, there is provided a semiconductor device further provided with an insulating film such as a TEOS (tetraethoxy silane) SiO2 film on a semiconductor device provided with a resistor on the active region, formed with electrodes on the resistor through contact holes formed in the insulating film. Thus, the first object is achieved.
Further, in the present invention, by having a resistor formed on the active region through the insulating film with a leveled top surface as a structural component of a ladder circuit, the first object is achieved.
Further, in the present invention, on the insulating film which has a leveled surface and is formed on the active region, the resistor is formed from a substance selected from the group consisting of a mixture of Ni and Cr, CrSiO, CrSiN, CrSiON, xc3xa2-FeSi, amorphous silicon, polycrystalline silicon, WSi, TiN, W, TaN, and a mixture of Mo and Si, or a two layer formed of Ti and TiN, or Ti and WN, to obtain a satisfactory resistor, thereby achieving the first object.
Further, in the present invention, the resistor formed on the insulating film which has a leveled surface and is formed on the active region, is formed with a film thickness range of 50 to 4000 xc3x85, preferably 100 to 1000 xc3x85, and more preferably 200 to 700 xc3x85 to form a resistor with higher specific accuracy, thereby achieving the first object.
Further, in the present invention, a resistivity of the resistor formed on the insulating film which has a leveled surface and is formed on the active region, is in a range of 1 to 1 M xcexa9/xe2x96xa1, and preferably 1 to 50 k xcexa9/xe2x96xa1 so that the resistor with a high specific accuracy may be obtained, thereby achieving the first object.
Further, in the present invention, there is provided a method of manufacturing a semiconductor device, including the steps of forming a semiconductor element on a semiconductor substrate, then forming an insulating film on the semiconductor element, leveling the surface of the insulating film by, for example, CMP (chemical mechanical polishing) with the vertical interval within 20%, preferably within 10% of the film thickness of the interlayer film, forming the film of the resistor on the top surface of the leveled insulating film, and patterning the resistor on the active region from the film of the resistor, thereby achieving the second object. With CMP, using a slurry including a chemical action and combining chemical etching, a level surface without damage may be obtained.
Further, in the present invention, there is provided a method of manufacturing a semiconductor device, including the steps of forming a semiconductor element on a semiconductor substrate, then forming an insulating film on the semiconductor element, leveling the top surface of the insulating film, forming a film of the resistor on the top surface of the leveled insulating film, patterning the film of the resistor and forming the resistor on the active region of the insulating film, and forming electrodes to both end portions of the resistor, to thereby achieve the second object. The resistor is formed by, for example, isotropic etching.
Further, in the present invention, there is provided a method of manufacturing a semiconductor device, including the steps of forming a semiconductor element on a semiconductor substrate, forming an insulating film on the semiconductor element, leveling the surface of the insulating film by CMP or the like, forming a film of the resistor on the top surface of the leveled insulating film, forming a protective film to protect the resistor in performing anisotropic etching of electrodes on the film of the resistor, patterning the film of the resistor and the protective film to form a resistor provided thereon with the protective film in an active region of the insulating film, anisotropically etching both end portions of the protective film using, for example, SiO2 (silicon oxide) as a mask for exposure of portions for forming electrodes on both end portions of the resistor, forming the electrodes on both the end portions of the resistor which are exposed from the protective film by anisotropic etching, to thereby achieve the second object. By anisotropic etching of the electrodes, the electrodes may be made compact.
Further, in the present invention, there is provided a method of manufacturing a semiconductor device, including the steps of forming a semiconductor element on a semiconductor substrate, then forming a first insulating film on the semiconductor element, leveling the surface of the first insulating film by CMP or the like, forming a resistor in the active region on the top surface of the leveled insulating film, forming a second insulating film on the resistor, forming contact holes reaching the side surface portions of both end portions of the resistor, in the second insulating film, and forming electrodes in the side surface portions of both the end portions of the resistor through the contact holes, to thereby achieves the second object. In this method, the electrodes may be formed relatively with ease.
Further, in the present invention, there is provided a method of manufacturing a semiconductor device comprising the steps of forming a semiconductor element on a semiconductor substrate, forming a first insulating film on the semiconductor element, leveling the surface of the first insulating film by CMP or the like, forming a film of the resistor on the top surface of the leveled insulating film, forming a film to control the etching speed on the film of the resistor to prevent the contact hole from penetrating the resistor, patterning the resistor and the controlling film which controls the etching speed and forming the resistor provided with the controlling film at the top surface in the active region on the insulating film, forming a second insulating film which is etched faster than the controlling film on the resistor, forming contact holes reaching the top surface portions of both end portions of the resistor in the second insulating film, and forming electrodes at the top surface portions of both end portions of the resistor through the contact holes, to thereby achieve the second object. With this method, when the contact hole formed in the resistor and, for example, a contact hole deeper than the contact hole formed on the electrode below the first insulating film, are simultaneously etched, the penetration of the contact hole through the resistor may be prevented.
Further, in the present invention, there is provided a method of manufacturing a semiconductor device, including the steps of forming a semiconductor element on a semiconductor substrate, then forming a first insulating film on the semiconductor element, leveling the surface of the first insulating film by CMP or the like, forming a resistor on the top surface of the leveled insulating film and in the active region, etching the first insulating film and making the first insulating film thin in regions other than the region where the resistor exists with the resistor as a mask, to form a second insulating film on the resistor, forming contact holes reaching the top surface portions of both end portions of the resistor, on the second insulating film, and forming electrodes at the top surface portions of both end portions of the resistor through the contact holes, to thereby achieve the second object. According to the present invention, the contact holes are prevented from penetrating through the resistor. In places other than the region where the resistor exists, the thickness of the first insulating film is thinned by etching, so that, for example, a contact hole may be formed for the electrode below the first resistor whilst preventing the penetration of the contact hole through the resistor.
Further, in the present invention, there is provided a method of manufacturing a semiconductor device comprising the steps of forming a semiconductor element on a semiconductor substrate, then forming a first insulating film on the semiconductor element, forming a contact hole, for example, reaching the electrode for the wiring of the ladder circuit below the insulating film in the insulating film, forming an electrode below the insulating film through the contact hole, leveling the surface of the insulating film by CMP or the like, forming a resistor in the active region of the top surface of the leveled insulating film so as to connect with the electrode formed in the contact hole, to thereby achieve the second object.
Further, in the present invention, the leveling of the insulating film formed in the active region may be performed by CMP, as well as by etchback and the like.
Further, in the present invention, there is provided a method of manufacturing a semiconductor device in which a temperature when forming the resistor film on the leveled insulating film is set to 450xc2x0 C. or less, whereby the deformation of the electrode formed below the insulating film may be prevented, thereby achieving the second object.